Aminoazo compounds of the benzimidazole series



United States Patent Ofiice 7 3,132,131 Patented May 5, 1964 3,132,131 AMINOAZO CQMPOUNDS F THE BENZHVHDAZOLE SERIES Hasso Hertel and Reinhard, Mohr, Olfenbach (Main),

Germany, assignors to Farbwerke Hoeehst Aktiengesellschaft vormals Meister Lucius & Eriining, Frankfurt am Main, Germany, a corporation or Germany No Drawing. Filed Dec. 18, 1961, Ser. No. 160,315

(ilalrns priority, application Germany Dec. 24, 1960 6 Claims. (Cl. 260-157) The present invent-ion relates to new aminoazo compounds of the benzim-idazole series of the general formula wherein R is a member of the group consisting of phenyl, lower alkylphenyl, lower alkoJdyphen-yl, chlorophenyl, methylchlorophenyl, methylnitrophenyl, methoxychlorophenyl, methoxynitrophenyl, chlorophenoxychlorophenyl,

N Ni;

in which R and R and R have the meanings indicated above. 1 As diazo components there may be used in the process of the present invention aromatic or heterocyclic amines which are norm-ally used for the manufacture of amdyestufis. As aromatic amines there may be mentioned cene or pyrene series which may contain in the aromatic nucleus substituents, such as halogen atoms, trifluoromethyl, hydroxyl, alkoxy, alkyl, carboxylic acid, carboxylic acid amide, carboxylic acid ester, sulfonic acid,

sulfonic acid amide, alkylsulfone, arylsulfone, acylamino,

alkylamino,dialkylaminqarylamino, Intro, acyl, cyano, aryloxy'or arylazo groups.

for example those of the benzene, naphthalene, anthra-r As heterocyelic amines there are used amino compounds which are capable of forming diazonium compounds. The diazotizable amino group may be bound to an aryl radical connected to the heterocyclic ring or directly to the heterocyclic ring. Compounds'of this kind are for example am-ino-carbazoles, amino-quinolines, amino diphenylene oxides, amino-benztriazoles, aminobenzthiazoles, amino-benzimi-dazoles, amino-tetrazoles, amino-triazoles, aminothiazoles, aminopyrazoles or amino-indazoles. 1

As coupling components there are used 7-amino-benzimidazoles of the aforesaid formula which can easily be obtained by reducing the corresponding 7-nitro-benzimidazoles, for example with iron and hydrochloric acid, or' by catalytic reduction. The 7-nitro-benzimidazoles can be prepared by known methods, for example by cyclization of 1-nitro-2,3-diaminobenzenes with aliphatic carboxylic acids of low molecular weight, such as formic acid, acetic acid or propionic acid, or by nitrating benzimidazoles of the general formula NH F.3

Cr-Rl R3 N in which R represents a hydrogen atom or an alkyl radical, R represents a halogen atom, an alkyl or alkoxy group and R represents a hydrogen or halogen atom, an alkyl or alkoxy group, with nitric acid in concentrated sulfuric acid at a temperature between about 2.0 C. and C.

The coupling of the diazonium compounds of the aromatic l or heterocyclic amines with the 7-amino-benzimidazoles to form the new aminoazo compounds can be conducted by known methods. According to the capabil-ity of coupling of the diazonium compound the coupling may be carried out in a neutral, acid or alkaline aqueous solution or suspension. In some cases it is suitable to conduct the coupling in the presence of organic solvents, such as acetic acid, alcohols, ketones, d-imethylfomiamide or pyridine. The aminoazo compounds can be isolated in the form of the free bases or in the form a of their salts, for example as hydrochlorides or sulfates.

The new compounds are colored crystals. They may be used as dyestuffs or intermediates for the manufacture of dyestuffs. They are suitable for example, if desired,

I after acylation, oxalkylation or cyanoalkylation of the amino group, as disperse dyestuffs for dyeing synthetic fibers, such as polyamide, polyurethane, polyester or acetylcellulose fibers.

The following examples serve. to illustrate the present invention, the parts being by weight unless otherwise stated, and the relationship of parts by weight to parts by volume being the same as that of the kilogram to the liter.

Example 1 147 parts of 7-amino-5-methy1benzimidazole are dissolved in 2000 parts by volume of water'and 350 parts by volume of hydrochloric acid of 20 B. To this solution a diazo solution is added which is prepared in the usual manner from 93 parts of aniline, 290 parts by volume of hydrochloric acid of 20 B. and 69 parts of sodium nitrite. By slowly dropping in an aqueous solution of 750 parts of crystallized sodium acetate, the aminoazo compound separates in crystalline form. When the coupling is complete, the precipitated hydrochloride of the aminoazo compound of the formula @N-N NH. N NH OH is filtered 01f, washed and dried. The yield is nearly quantitative. The free aminoazo compound crystallizes in the form of golden-yellow plates melting at 222 C.

Example 2 175 parts of 3-amino-1-phenyl-5-imino-4,S-dihydro- 1,2,4-triazole are dissolved in a mixture of 1000 parts by volume of water, 500 parts by volume of nitric acid of 62.5% strength and 2000 parts of ice. The mixture is then diazotized at a temperature between 5 C. and 8 C. by the addition of 200 parts by volume of 5 N- sodium nitrite solution. After about 2 minutes the clear yellow diazo solution is introduced in one jet into a solution of 147 parts of 7-amino-5-methylbenzimidazole in 2000 parts by volume of water, 500 parts of ice and 300 parts by volume of 5 N-hydrochloric acid. The cou- U pling is complete after about 1 minute. The aminoazo compound obtained is filtered off, washed with a small quantity of cold water and dissolved in hot water. After filtering with some animal charcoal the aminoazo compound is separated in the form of the hydrochloride by the addition of concentrated hydrochloric acid. When the precipitation is complete, the hydrochloride is filtered oif, washed with a small quantity of cold water and methanol and dried at C. 340 parts of the dihydrochloride of the aminoazo compound of the formula are obtained in the form of red crystals.

R211 RN=N NH 2 N\ /NH E R1 which can be obtained in accordance with the process of the present invention.

R R Rn Rap Melting point, G.

Z-methoxy-fi-nitrohydrogen. hydrogen. methy1. 305 to 307.

phenyl. 2-rnethy1phenyl .do do ..do 230 to 231 5 2-methyl-4-ehloroo 0------ 0 226 to 228 phenyl. 2-methoxypheuyl do do do 243 to 245 7 2-methoxy-5-chlorodo do do 260 to 260.5

p en 2-ehloropheny1 do do .do 233 to 235 2-methyl-5-nitro- -.do. do do 285 to 287 phenyl. 2-rnethyl-6-chlorodo do do 320 benzimidazolyl- (7) R R R20: R25 Melting point, C.

4-methoxyphenyl hydrogen. hydrogen. methyl" 258 to 259 Naphthyl-(1) o o do 244 to 246 2-methoxy-4-chlorodo do.- do.-- 249.5 to 251 phenyl. 2-choloro-5-methyl- 229 to 230 phenyl. 3-m 253.5 to 255 ethylphenyl phenyl. 2(4-chlorophenoxy)- .do .--do 5-chlorophenyl. 4-acetylphenyl do do 2-methoxy-5-chl0rohydrogen. methoxyphenyl. 2-methoxyphenyl do do 2-methoxy-5-uitrodo do phenyl. Phenyl .--do hydrogen. 4-sulfophenyl do... do

Do methyl methylm- Do hydrogen. Anthraquinonyl-(1) methyl 2-rnethyl-5-nitroo do phenyl.

2-methoxy-4-nitro do- -do .do 255 phenyl.

2-methoxy-5-nitrohydrogenhydrogen. ethyl 147 to 148 phenyl.

We claim:

1. Aminoazo compounds of the formula wherein R is a member of the group consisting of phenyl, lower alkylphenyl, lower alkoxyphenyl, chlorophenyl, methylchlorophenyl, methylnitrophenyl, methoxychlorophenyl, methoxynitrophenyl, chlorophenoxychlorophenyl, acetylphenyl, rsulfophenyl, naphthyl, anthraquinoyl, methylchlorobenzimidoazolyl and 1-pheny1-5-im-ino-4,5-dihydro-1,2,4-triaz0lyl radical; R is a member of the group consisting of hydrogen, hydroxyl and lower alkyl; and R and R are members of the group consisting of hydrogen, lower alkyl and lower alkoxy, at least one of the substituents R and R being a member of the group consisting of lower alkyl and lower alk-oxy.

2. The aminoazo compound of the formula 4. The aminoazo compound of the formula 1 '7 v N NH 7 1 6. The aminoazo compound of the formula 0 CHa C 3 References Cited in the file of this patent UNITED STATES PATENTS 2,308,023 Peterson Jan; 12, 1943 2,475,506 Lewis July 5, 1945 2,479,944 Lewis Aug. 23, 1949 2,671,775 Hanhart Mar. 9, 1954 

1. AMINAOZO COMPOUNDS OF THE FORMULA 